Abstract

We report on the assembly of an off-axis reflective imaging system employing freeform, φ-polynomial optical surfaces. The sensitivity of the system to manufacturing errors is studied for both a passive and active alignment approach. The as-built system maintains diffraction-limited performance in the long-wave infrared.

As-built subassemblies for the (a) primary, (b) secondary, and (c) tertiary mirrors of the three mirror system that are to be mated to the optical housing. (d) Three mirror optical system with subassemblies mounted to the housing.

(a) Measured wavefronts for a 3×3 grid of field points spanning an 8mm×6mm FOV for the directly assembled optical system and (b) with the secondary mirror tilted roughly 1 arc min with a 23 μm shim. The RMSWFE in micrometers is displayed within the wavefront for each field.